I was interested in going back to research past discussions on the
list about possibilities for a syntax to add a class="foo" to div's
and/or span's to Markdown text, but didn't have much luck.

IIRC, the list never had a searchable web interface, but older posts
were available on a Google search. This seems not to be the case any
more. Can anyone recommend a good way to search the archives of this
list?